Cork composition



atented Apr. 8, 1941 CORK COMPOSITION Charles Dangelmajer, Dover, N. 3.,and Edgar S. Peierll, New York, N. Y., assignors to BesistoflexCorporation, New York, N. Y., a corporation of New York No Drawing.

Application May 8, 1939,

Serial No. 272,398

8 Claims.

The present invention relates to cork compositions of the typecontaining the cork in the form of particles held together by a binderinto a solid plastic mass.

In Schnabel and Dangelmajer application Serial No. 288,754, filed April19, 1939, polyvinyl alcohol compositions of improved plasticity aredescribed which, while making use in the usual manner of a solvent forthe polvinyl alcohol, are essentially characterized by their use of thissolvent in conjunction with dispersed particles of substantiallynon-volatile organic substances substantially incapable of dissolving inthe soltent or of dissolving the polyvinyl alcohol. These substances intheir dispersed state produce a plasticizing effect which can beregarded as in the nature of an internal lubrication of the entire massof material plasticized. The solvent for the polyvinyl alcohol isrequired in these com positions, but the need of retaining it isconsiderably reduced by the insoluble organic substances employed in astate of dispersion. The term mechanical plasticizers has appropriatelybeen applied to these dispersed insoluble substances to distinguish themfrom the usual plasticizers employed in a state of solution in polyvinylalcohol compositions.

It has now been found that compositions of improvedntility, adaptablefor use in a wide rangeof applications, may be made by combinin: corkparticles with polyvinyl alcohol compositions which contain mechanicalplasticizers.

Polyvinyl alcohol, thus plasticized, has been discovered to be anexcellent binder for cork particles and at the same time the inclusionof the cork has been found to improve the physical characteristicsof'the polyvinyl alcohol composition,

in a number of respects. Plasticized polyvinyl alcohol is flexible,resilient and somewhat elastic, but when subjected to continued pressurehas a tendency to cold-flow or take on a permanent set. By incorporatingcork particles in the composition this tendency is decreased and theresiliency is greatly improved. The inclusion of cork also izes theweight of the product and improves, its resistance to elevatedtemperatures. Moreover, since polyvinyl alcohol is relatively expensive,the cost of the final product is much less when cork is included insubstantial amounts.

The use, of the aforementioned polyvinyl alcohohcompositions as thebinder for cork particles is particularly advantageous because thebinder itself, in addition to being flexible, elastic and resilient, isunaffected by oils, fluid fuels and most organic solvents. The productsof the invention are therefore particularly useful where they come incontact with such liquids. as for example, in fuel supply systems and inthe handling of solvents.

The cork compositions of the invention are 7 each of which may consistof one or more of the suited generally for the manufacture of gaskets,packings and washers. They may be used as blankets for the printingindustry, as resilient supports for machinery, as bottle cap liners, asvalve seats of the washer type, and many other items having a widevariety of shapes and sizes. A wide variety of materials are availablefor use as the mechanical plasticizers to be contained in the polyvinylalcohol binding compositions employed in accordance with the invention.Oils and fats of various types may be thus used. Other materials includevarious natural and synthetic hydrocarbons and their polymers, thehigher fatty acids and their esters, the esters of various other acids,the higher alcohols, and various compounds of the terpene group. Evensuch materials' as natural and artificial resins and rubbers may beused. In view of the pronounced hydrophobic properties of oils, however,these are particularly well qualified for use in the polyvinyl alcoholbinding compositions. The type of oil used is of no great importance.animal origin may be used. They may be nondrying, such as sesame oil orpeanut oil; or semidrying, such as castor oil; or drying, such aslinseed oil or wood oil. Oxidized or-unoxidized oils may be used,'aswell as polymerized oils.

The solvent for the polyvinyl alcohol in the binding compositionsemployed by the invention may consist of a single substance, such aswater alone, formamide alone, etc., or of a mixture of substances, suchas water and formamide, water and glycerine, etc., it being understoodthat it may include any of the soluble organic substances commonlyusedfor obtaining plasticity in polyvinyl alcohol compositions. a

The binding compositions employed by the in vention are not restrictedto the use of a single mechanical plasticizer. In this connection itshould be noted that the use of miscible substances results in theirbeing dispersed in admixture with one another, while the useofimmiscible substances results in their being dispersed independently ofone another. The binding compositions employed by the invention may thuscontain a plurality or mechanical plasticizers,

organic substances referred to above.

In producing the products of the invention, the insoluble substance orsubstances which are to constitute the mechanical plasticizing means inpolyvinyl alcohol as an emulsifying agent, al-

though other emulsifying substances may be used, such as Irish moss,Turkey-red oil, amine soaps .etc. Subsequent to this emulsification, thede-.

Oils of mineral, vegetable, or

sired proportions of cork particles and polyvinyl alcohol may then bethoroughly admixed with the emulsion, it being noted in this connectionthat polyvinyl alcohol is normally a powder, in which'state it may beused for this admixture. The result is thus an intimate mixture ofemulsion moistened particles of cork and polyvinyl alcohol, whichmaythen be reduced into a shapable plastic mass in various ways, as bymastication through rollers, kneading under heat, etc., the shapablemass obtained consisting of cork particles held together by a polyvinylalcohol binder mechanically plasticized by the insoluble substance orsubstances employed. Subsequently, this material may be processed intothe products desired, as by moulding.

It is understood, however, that the invention is not restricted toproducts obtained in the above manner. In certain cases, for example,the insoluble substance or substances used as the mechanical plastioizermay be satisfactorily dispersed in the solvent for the polyvinyl alcoholwithout emulsitlcation. Moreover, there are certain types of substanceswhich may be used to provide mechanical plasticity without beingpreliminarily dispersed in the solvent for the polyvinyl alcohol,particularly such materials as rubbers and resins. In these cases, ofcourse, a plastic mass of polyvinyl alcohol may first be produced in theordinary way in the absence of the insoluble substance or substancesused for pro- ,ducing prolonged plasticity, subsequent to which thelatter may be introduced together with the cork particles by simplemastication. It is thus clear that the invention is not restricted toproducts obtained in any particular manner.

The size of the cork particles contained in the products of theinvention may vary within wide limits. As an upper limit, for example,they may well exceed an overall dimension of V inch. As a lower limit,they may be of the size of an air blown. powder of ZOO-mesh and evenfiner. Of course, the choice of particle size will be largely dictatedby the use to which.the product of the invention is to be applied.

Certain specific embodiments of the invention will now be described byway of illustration, it

paniy) 30 Viscous oil #32 (a hydrocarbon polymer sold by the StandardOil Company of California) 2o 4% solution of polyvinyl alcohol 200.Formamlde a 150 Glycerine 250 Urea 4 20 Water 550 The polyvinyl alcoholsolution was used at this stage merely to emulsify the three oils in thewater, for which purpose a, grade of polyvinyl alcohol of high viscosityand high saponification number was employed. The mechanical plasticizingmeans was obviously provided by these oils alone, the formamide,glycerine and urea being employed as plasticizing means of the usualsoluble type. This emulsion was employed in the following mixtures:

Coarse grade of cork (about d-mesh) Cork "grams" 50 50 50 Polyvinylalcohol (powder) do 50 1'7 mulsion do 75 37.5 25.5

Medium grade of cork (about Ill-mesh) Cork grams 50 50 Polyvinyl alcohol(powder) do 50 25 1'1 Emulsion do 37.5 25.5

Fine grade of cork (air blown powder of about ZOO-mesh) Cork grams '7575 Polyvinyl alcohol (powder) -do '15 37.5 Emulsion do.. 112.5 58.25

In producing these mixtures, the cork particles were thoroughly admixedwith the powdered polyvinyl alcohol prior to carrying out the ad to coolunder pressure.

mixture with the emulsion. As will be noted, there was no appreciablevariation in the ratio of polyvinyl alcohol to emulsion in these variousmixtures, but the proportion of cork varied considerably for each of thethree grades employed, especially the coarse and the medium grades.

The foregoing mixtures were first reduced to plastic sheets by milling.Thereafter, the sheets were pressed in a chromium plated mold under 2000lbs. gage pressure at a temperature of from to 0., the pressed sheetsbeing allowed The various products thus obtained were all usefulflexible products.

Another emulsion was prepared of the following ingredients:

Grams Vultex" (a. neoprene latex containing 20% solldsi) 150 Stand oil(oxidized linseed oil).... 21 Mineral oil 8 Turpentine 6 4% aqueoussolution of polyvinyl alcohol 90 Glycerine The water in this emulsionwas provided in the latex and in the polyvinyl alcohol solution. Here,

the latex, linseed oil, mineral oil and turpentine constituted themechanical plasticizing means. As before, the polyvinyl alcohol solutionwas employed to emulsify these various substances in the water, theglycerine being employed alone as a. soluble plastici'zer. The followingmixtures were subsequently produced:

In the same manner as before, these mixtures were successfully processedinto useful flexible products.

It is to be understood that the invention is not limited to the featuresherein specifically described by way of illustration but can be carriedout in various other ways within the purview of the invention.

"What is claimed is:

i. A flexible and resilient cork composition unaffected by oils andfluid fuels comprising cork particles and a binder for said particles,said binder comprising polyvinyl alcohol, a solvent for i the polyvinylalcohol, and a substantially nonvolatile oil in dispersed state, saidsolvent being substantially incapable of dissolving said oil.

2. ll. flexible and resilient cork composition.

unaffected by oils and fluid iuels comprising cork particles and abinder for said particles, said binder comprising polyvinyl alcohol, asolvent for the polyvinyl alcohol, and a plurality of substantiallynon-volatile oils in dispersed state, said solvent being substantiallyincapable of dissolving said oils,

A flexible and resilient cork composition unadected by oils and iiuidfuels comprising cork particles and a binder for said particles,

said binder comprising polyvinyl alcohol, a solcapable of dissolving 5.A flexible and resilient cork composition unaffected by oils and fluidfuels comprising cork particles and a binder for said particles, saidbinder comprising polyvinyl alcohol, a solvent for the polyvinylalcohol, and an oxidized drying oil in dispersed state, said solventbeing substan tially incapable of dissolving said oil.

6. A flexible and resilient cork composition unaffected by oils andfluid fuels comprising cork particles and a binder for said particles,said binder comprising polyvinyl alcohol, a solvent for the polvyinylalcohol, and linseed oil in dispersed state, said solvent beingsubstantially incapable of dissolving said oil.

7. A flexible and resilient cork composition unaffected by oils andfluid iuels comprising cork particles and a binder for said particles,said binder comprising polyvinyl alcohol, a solvent for the polyvinylalcohol, and a resin in dis- 1 persed state, said solvent beingsubstantially incapable of dissolving said resin.

8. A flexible and resilient cork composition unafiected by oils andiluid fuels comprising cork particles and a binder for said particles,said binder comprising polyvinyl alcohol, a solvent for the polyvinylalcohol, and rubber in dispersed state, said solvent being substantiallyinsaid rubber.

'S DANGELMAJER.

S, PEllERLS.

C i EDGAR

